sorry nope.
one thing I can be sure it covers very specific use scenario.
the videos used to work on KP 49. After updating to KP50 my device come in weird state. after one or two reboots the state vanished, so i couldn't reproduce it anymore. (it started to work properly as my device was in usual state).

I know that some uses of player triggered bugs in this state while other were perfectly okay. As MediaBox is only a wrapper and it uses backends from another players, I believe the difference was a backend, since codecs used for both videos triggered different backends (Mediabox basing on config and media type can choose backend automatically).

Videos was just some people playing the instrument on youtube. The videos were directly downloaded from youtube (using a pc browser) and no changes were done since then. (the videos are SD quality but not scaled for the device). I even have two videos with same contents but one a flv and one an MP4 I believe (different copies from youtube server of same video). As formats were different and I mostly remember my config I'm sure one of triggered MAFW backend and the another triggered MPLAYER backend. But since the state which was able to trigger a bug was temporal, after rebooting I couldn't reproduce anymore (the baddie was reseted to something more rational). I may try to reproduce the same enviroment but even then I may fail to reproduce.

So I'm useless to help, until someone trigger the same.